getid3_lpac Class Reference

Collaboration diagram for getid3_lpac:

Public Member Functions
	getid3_lpac (&$fd, &$ThisFileInfo)

Detailed Description

Definition at line 18 of file module.audio.lpac.php.

Member Function Documentation

getid3_lpac::getid3_lpac	(	&	$fd,
		&	$ThisFileInfo
	)

Definition at line 21 of file module.audio.lpac.php.

References getid3_lib\BigEndian2Int().

                                                   {

                fseek($fd, $ThisFileInfo['avdataoffset'], SEEK_SET);
                $LPACheader = fread($fd, 14);
                if (substr($LPACheader, 0, 4) != 'LPAC') {
                        $ThisFileInfo['error'][] = 'Expected "LPAC" at offset '.$ThisFileInfo['avdataoffset'].', found "'.$StreamMarker.'"';
                        return false;
                }
                $ThisFileInfo['avdataoffset'] += 14;

                $ThisFileInfo['fileformat']            = 'lpac';
                $ThisFileInfo['audio']['dataformat']   = 'lpac';
                $ThisFileInfo['audio']['lossless']     = true;
                $ThisFileInfo['audio']['bitrate_mode'] = 'vbr';

                $ThisFileInfo['lpac']['file_version'] = getid3_lib::BigEndian2Int(substr($LPACheader,  4, 1));
                $flags['audio_type']                  = getid3_lib::BigEndian2Int(substr($LPACheader,  5, 1));
                $ThisFileInfo['lpac']['total_samples']= getid3_lib::BigEndian2Int(substr($LPACheader,  6, 4));
                $flags['parameters']                  = getid3_lib::BigEndian2Int(substr($LPACheader, 10, 4));

                $ThisFileInfo['lpac']['flags']['is_wave'] = (bool) ($flags['audio_type'] & 0x40);
                $ThisFileInfo['lpac']['flags']['stereo']  = (bool) ($flags['audio_type'] & 0x04);
                $ThisFileInfo['lpac']['flags']['24_bit']  = (bool) ($flags['audio_type'] & 0x02);
                $ThisFileInfo['lpac']['flags']['16_bit']  = (bool) ($flags['audio_type'] & 0x01);

                if ($ThisFileInfo['lpac']['flags']['24_bit'] && $ThisFileInfo['lpac']['flags']['16_bit']) {
                        $ThisFileInfo['warning'][] = '24-bit and 16-bit flags cannot both be set';
                }

                $ThisFileInfo['lpac']['flags']['fast_compress']             =  (bool) ($flags['parameters'] & 0x40000000);
                $ThisFileInfo['lpac']['flags']['random_access']             =  (bool) ($flags['parameters'] & 0x08000000);
                $ThisFileInfo['lpac']['block_length']                       = pow(2, (($flags['parameters'] & 0x07000000) >> 24)) * 256;
                $ThisFileInfo['lpac']['flags']['adaptive_prediction_order'] =  (bool) ($flags['parameters'] & 0x00800000);
                $ThisFileInfo['lpac']['flags']['adaptive_quantization']     =  (bool) ($flags['parameters'] & 0x00400000);
                $ThisFileInfo['lpac']['flags']['joint_stereo']              =  (bool) ($flags['parameters'] & 0x00040000);
                $ThisFileInfo['lpac']['quantization']                       =         ($flags['parameters'] & 0x00001F00) >> 8;
                $ThisFileInfo['lpac']['max_prediction_order']               =         ($flags['parameters'] & 0x0000003F);

                if ($ThisFileInfo['lpac']['flags']['fast_compress'] && ($ThisFileInfo['lpac']['max_prediction_order'] != 3)) {
                        $ThisFileInfo['warning'][] = 'max_prediction_order expected to be "3" if fast_compress is true, actual value is "'.$ThisFileInfo['lpac']['max_prediction_order'].'"';
                }
                switch ($ThisFileInfo['lpac']['file_version']) {
                        case 6:
                                if ($ThisFileInfo['lpac']['flags']['adaptive_quantization']) {
                                        $ThisFileInfo['warning'][] = 'adaptive_quantization expected to be false in LPAC file stucture v6, actually true';
                                }
                                if ($ThisFileInfo['lpac']['quantization'] != 20) {
                                        $ThisFileInfo['warning'][] = 'Quantization expected to be 20 in LPAC file stucture v6, actually '.$ThisFileInfo['lpac']['flags']['Q'];
                                }
                                break;

                        default:
                                //$ThisFileInfo['warning'][] = 'This version of getID3() only supports LPAC file format version 6, this file is version '.$ThisFileInfo['lpac']['file_version'].' - please report to info@getid3.org';
                                break;
                }

                $dummy = $ThisFileInfo;
                $riff = new getid3_riff($fd, $dummy);
                $ThisFileInfo['avdataoffset']                = $dummy['avdataoffset'];
                $ThisFileInfo['riff']                        = $dummy['riff'];
                $ThisFileInfo['error']                       = $dummy['error'];
                $ThisFileInfo['warning']                     = $dummy['warning'];
                $ThisFileInfo['lpac']['comments']['comment'] = $dummy['comments'];
                $ThisFileInfo['audio']['sample_rate']        = $dummy['audio']['sample_rate'];

                $ThisFileInfo['audio']['channels']    = ($ThisFileInfo['lpac']['flags']['stereo'] ? 2 : 1);

                if ($ThisFileInfo['lpac']['flags']['24_bit']) {
                        $ThisFileInfo['audio']['bits_per_sample'] = $ThisFileInfo['riff']['audio'][0]['bits_per_sample'];
                } elseif ($ThisFileInfo['lpac']['flags']['16_bit']) {
                        $ThisFileInfo['audio']['bits_per_sample'] = 16;
                } else {
                        $ThisFileInfo['audio']['bits_per_sample'] = 8;
                }

                if ($ThisFileInfo['lpac']['flags']['fast_compress']) {
                         // fast
                        $ThisFileInfo['audio']['encoder_options'] = '-1';
                } else {
                        switch ($ThisFileInfo['lpac']['max_prediction_order']) {
                                case 20: // simple
                                        $ThisFileInfo['audio']['encoder_options'] = '-2';
                                        break;
                                case 30: // medium
                                        $ThisFileInfo['audio']['encoder_options'] = '-3';
                                        break;
                                case 40: // high
                                        $ThisFileInfo['audio']['encoder_options'] = '-4';
                                        break;
                                case 60: // extrahigh
                                        $ThisFileInfo['audio']['encoder_options'] = '-5';
                                        break;
                        }
                }

                $ThisFileInfo['playtime_seconds'] = $ThisFileInfo['lpac']['total_samples'] / $ThisFileInfo['audio']['sample_rate'];
                $ThisFileInfo['audio']['bitrate'] = (($ThisFileInfo['avdataend'] - $ThisFileInfo['avdataoffset']) * 8) / $ThisFileInfo['playtime_seconds'];

                return true;
        }

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The documentation for this class was generated from the following file:

• Services/MediaObjects/getid3/getid3/module.audio.lpac.php